This invention relates generally to a combustion enhancing device for an internal combustion engine and, more specifically, to a device for insertion within the air intake system of a two cycle engine and related process which results in more complete combustion as evidenced by increased engine rpm.
The subject of improving combustion engine efficiency and reducing a harmful emissions continues to be of major concern not only from a fuel conservation standpoint but also from an environmental standpoint, since inefficient or incomplete combustion produces harmful emissions, principally in the form of unburned hydrocarbons.
There have been many attempts to improve or enhance combustion efficiency by the utilization of various devices or "add-ons" which are generally designed for incorporation within the intake system, between the carburetor and the combustion chamber.
For example, Hanff (4,015,574) discloses a plate with radial spokes which is positioned between the carburetor outlet and the intake manifold, and is utilized for creating turbulence in the fuel air mixture. The plate is intended to improve engine efficiency and decrease automotive pollutants.
Ong (4,307,697) discloses a device or insert which is located in the inlet manifold with an internal combustion engine and which is provided with protrusions on its interior surface. The device is said to improve the efficiency of the engine by creating complex swirls in the air fuel mixture downstream of the carburetor.
Williams (4,463,742) discloses a fuel economizer in the form of an insert which fits between the carburetor and the inlet manifold and which has a plurality of protrusions extending into the fuel/air stream.
Linder (4,474,163) discloses an apertured shield for improving the combustion in an internal combustion engine. The shield includes a plurality of spring tongues directed radially inward, and the shield is positioned in close proximity to an injection valve to cause turbulence in the flow into the combustion chamber.
Dooley (4,492,212) discloses an insert positioned in the intake manifold of an internal combustion engine for increasing turbulence and for improving the efficiency of the engine. The insert is located downstream of the carburetor.
Holderle (4,711,225) discloses a connecting piece for insertion between the carburetor and the combustion chamber of an internal combustion engine for minimizing fuel film on the inner surface of the connector. The device is apparently designed to prevent fuel film deposited on the inner wall of the connecting piece from being completely aspirated all at once into the combustion chamber which would cause over-enrichment of the mixture and hence a drop in rpm. This patent mentions specific applicability to two cycle chain saw engines.
Caughran (4,712,526) discloses the use of a turbine insert to create turbulence in the air/fuel mixture, designed for mounting on the piston head.
Litjens (4,836,151) also discloses the utilization of a turbine fan in a two cycle internal combustion engine.
The following patent documents also disclose various kinds of insert devices located downstream of the carburetor: 4,228,770; 4,295,458; 4,474,145; 4,690,107; and 4,879,976.
To date, these devices have not been particularly successful, particularly as far as two-cycle engines are concerned. Moreover, the insertion and/or removal of such devices is costly and time consuming.
The problem as it pertains to two-cycle engines has been highlighted by proposed emissions regulations for such engines in the State of California, which regulations could result in the outright ban of two-cycle engines in that State. Since chain saws are driven by two-cycle engines, and in light of the importance of the timber industry in California, there is great concern for the prospect of lost jobs, revenues and so on, which would significantly and negatively impact on that State's economy.
The present invention seeks to provide a simple, low cost and easy-to-install (or remove) device for two-cycle engines which improves engine efficiency through more complete combustion, resulting in increased engine rpm and a decrease in emissions.
The invention specifically relates to an insert device, referred to herein as a "tuned air insert" which is located upstream of the carburetor, preferably in a coupler which typically extends between an air cleaner and the carburetor of a two-cycle engine.
The insert itself is generally formed as a tubular member (of one or more pieces) tapering from a larger inlet side to a smaller outlet side, with or without surface irregularities, i.e., ribs, flutes, etc., formed on its interior surface. It is contemplated that tuned air inserts of various lengths and diameters will be provided for different engine models consistent with the coupler designs generally used with such engines. Thus, the couplers and/or air cleaners could be provided with their own insert as an after-market purchase item, or the inserts can be sold separately for use with certain identified engine and/or saw models. While the inserts are described herein with specific application to two-cycle engines in chain saws, they are equally applicable with advantageous results in two-cycle engines used for other purposes as well, e.g., for driving other tools, carts, model airplanes, and the like.
It is critical in all cases that the tuned air insert be located such that its lower edge, i.e., on the outlet side, be raised above the coupler outlet and carburetor inlet, and that the coupler surrounding the tuned air insert have a diameter sufficiently greater than that of at least a portion of the insert, so as to create a chamber surrounding the insert, immediately above and open to the carburetor inlet.
The space between the lower edge of the insert and the carburetor inlet, which serves as the opening to the chamber, may be varied by sliding the insert upwardly or downwardly within the coupler. Optimum location may be determined simply as a function of engine rpm and, once determined, can be used as the standard for all similar model engines.
The use of grooves, flutes or ribs (or other surface patterns) on all or part of the interior surface of the insert is an optional feature which may have beneficial effects in some engines as a result of turbulence created in the inlet air.
In all instances experienced to date, the use of an insert as described above has resulted in a significant increase in engine rpm, evidencing more efficient and more complete combustion, and necessarily resulting in a reduction in unburned hydrocarbon emissions.
Accordingly, in its broadest aspect, the present invention comprises an insert device for mounting in a coupler extending between an air cleaner and a carburetor inlet of an internal combustion engine, the device comprising a tapered body portion extending between a larger diameter inlet end and a smaller diameter outlet end.
In another aspect, the present invention comprises: a coupling for use in connecting an air cleaner and a carburetor of an internal combustion engine, the coupling being of tubular construction having an inlet end for attachment to an outlet end of an air cleaner, and an outlet end for attachment to a planar surface surrounding an inlet of the carburetor, the outlet end of the coupling having a flat annular surface adapted for flush engagement with the planar surface; and a tubular insert within the coupling, the insert tapering in a longitudinal direction from a larger diameter inlet end to a smaller diameter outlet end, the smaller diameter outlet end terminating an adjustable distance above the flat annular surface of the coupling.
In still another aspect, the present invention comprises: an internal combustion engine having a carburetor including a carburetor inlet and an air conduit connected to the carburetor inlet for introducing air to be mixed with fuel in the carburetor, a combustion enhancing and emissions reduction device located within the air conduit, the device comprising a tubular member having interior and exterior surfaces which taper inwardly from a larger diameter inlet end, the larger diameter inlet end being engaged with the air conduit so that air flowing through the conduit is directed through the tubular member, the smaller diameter outlet end being axially spaced from the carburetor inlet so as to create a chamber open at one end and surrounding the tubular member immediately upstream of the carburetor inlet.
In terms of a process, the present invention provides a method of improving the combustion efficiency and reducing emissions in an internal combustion engine having a carburetor including a carburetor inlet and an air conduit connected to the carburetor inlet comprising the steps of:
a) establishing a primary flow path for air passing through the air conduit to the carburetor inlet; PA1 b) establishing a chamber at leas partially surrounding the primary flow path along at least a portion of the air conduit, the chamber having an opening communicating with the primary flow path at a location immediately upstream of the carburetor inlet; and PA1 c) adjusting the opening as a function of engine rpm.
As disclosed further herein, individual inserts will vary in design to be compatible with different two-cycle engines.
Other objects and advantages of the invention will become apparent from the detailed description which follows.